Insulator



June 15, 1948. J. J. TAYLOR 2,443,436

INSULATOR Filed Aug. 23, 1945 Jays INVEN TOR. JaH/v J. 77m OR.

Patented June 15, 1948 INSULATOR John J. Taylor, Wadsworth, Ohio, assignor to The Ohio Brass Company, Mansfield, Ohio, a corporation of New Jersey Application August 23, 1945, Serial No. 612,173

This invention relates to line insulators and, more particularly, insulators of the suspension type.

In the insulator of this invention the dielectric body is composed of porcelain or glass or other vitreous material, is usually disc shaped, and is formed with a recess. The head of a pin, generally a steel pin, although it may be made of other metal, is held in the recess by cement or other suitable bonding material.

The invention has for its object the provision of moisture-resistant, resilient cushioning means around the pin at the level of the lower surface of the cement or other bonding material to prevent the cracking of the dielectric due to growth of the pin as it corrodes.

The invention is exemplified in the combination and arrangement of the parts shown in the accompanying drawing and described in the accompanying specification, and it is more particularly pointed out in the appended claim.

In the drawing:

Fig. 1 is an elevation with parts in section showing one embodiment of the invention;

Fig. 2 is a fragmentary elevation, largely in section, showing a modified form of the invention; and

Fig. 3 is a further fragmentary elevation, largely in section, showing another modification.

In Fig. 1 the dielectric disc 5, which is composed of porcelain, is surrounded by the metal cap 6, and the head of the steel pin 1 is embedded in Portland cement 8 in the recess 9 of the dielectric. The vertical wall of the recess is sanded at ID to improve the bond between the cement and the porcelain. The outer vertical wall of the dielectric is similarly sanded at [2 to improve the bond between it and the cement I3 which fills the space between the dielectric disc and the metal cap 6.

Ozone, nitrous oxide, and other gases formed by any electrical discharge that may take place from the pin are pocketed by the petticoats l of the dielectric. Such gases accelerate corrosion of the steel or other pin below the level of the lower surface of the cement 8. As corrosion of the pin progresses, it travels axially up the pin, under the cement; and as the diameter of the pin increases, pressure applied against the cement is transmitted to the dielectric disc. It is an object of the invention to provide a moistureresistant, resilient cushioning material around the pin at the level of the lower surface of the cement or other bonding material to absorb the radial pressure exerted by enlargement of the pin as it corrodes.

According to the embodiment illustrated in Fig. 1, the rubber cushion l! is provided for this purpose. This cushion surrounds the pin. It is preferably composed of neoprene but may be 1 Claim. (Cl. 174-482) made of natural rubber or other rubber-like synthetic. It is customary to galvanize the surface of the steel pin of an insulator of this type to retard corrosion. It is, therefore, generally necessary to bond the rubber cushioning material to the galvanized surface. There are various means for accomplishing this. One satisfactory method of forming the bond is to coat the galvanized surface with Pliobond (an adhesive manufactured by The Goodyear Tire & Rubber Company) or a similar curable adhesive suitable for bonding rubber to metal, then coat the adhesive-surfaced pin with a cushion of vulcanizable rubber compound, and then cure the cushioning material in place.

If the cushioning material is adjacent the pin as it is in the arrangement shown in Fig. 1, it is desirable to have it extend somewhat below the level of the lower surface of the cement. This retards corrosion of the pin under the cement; and as it is only this corrosion which presses against the cement and eventually damages the dielectric, such an arrangement of the cushioning material lengthens the life of the insulator. The dielectric disc is protected by the cushion of rubber I! because the rubber is more resilient than the cement and absorbs the pressure exerted against the cement by the enlargement or growth of the pin as corrosion proceeds.

It is not necessary that the cushion be made of rubber. The modulus of the steel pin is in the neighborhood of thirty million. The modulus of the porcelain disc is about ten million. The Portland cement filler has a modulus of two or three million. The modulus of rubber is much less than this. Any moisture-resistant, resilient material with a modulus less than the modulus of the cement or other bonding material employed will serve as a cushion to prevent or delay the application of sufficient pres-sure against the dielectric to damage it.

There is no reason for providing any cushion at the head of the pin to absorb pressure exerted by enlargement of the pin because the dielectric disc will be damaged before corrosion extends this far. The invention, therefore, provides cushioning only at the bottom of the bonding layer, and the cushioning material may be of any moisture-resistant, resilient composition with a lower modulus than the modulus of the bonding material.

It is not necessary that the cushion be adjacent the pin, and the insertion of an annular cushion of neoprene 20 or other rubber or moisture-resistant, resilient material in the lower surface of the cement or other bonding material, out of contact with both the pin and the disc, is illustrated in Fig. 2.

According to Fig. 3 the pressure produced by growth of the pin is absorbed by the plastictreated fabric 25 which is wrapped several times around the pin at the level of the bottom of the cement. The plastic is preferably a thermoset; such as Bakelite, etc., which may be cured in place. Any moisture-resistant, resilient plastictreated, fibrous material having a lower modulus-(- than the cement may be used.

It is apparent from the illustrations that'the nature of the cushioning materialand -itslocation may vary. The invention 'is notzlimited tothe details of the specific illustrations but is defined in the appended claim.

What I claim is:

An insulator comprising a vitreous dielectric member with a recess therein in which is the head ofa metal insulator pin embedded-inbonding material but with-the lower portion of the pin extending beyondthe bonding material, and at the lower surface of the bonding material and between the pin and the dielectric a band-oi moisture-resistant, resilient cushioning material which is relatively narrow as compared with the length of that portion -of-the pinabove said lower portion, and has a modulus less than the modulus of the bonding material, which cushioning material is at least as thick as several turns 'of-w-fabric so: as: tohave sufiioient resilience to' prevent cracking of the dielectric during appreciable growth of the pin as it corrodes.

JOHN J. TAYLOR.

REFERENCES CITED The following references are of record in the me of this patentz UNITED STATES PATENTS 

